There's a lot of debate about what exactly causes people to be obese. It seems very clear that there is a genetic aspect to it. However, it is also clearly tied to behavior since people around the world have been getting fatter lately. Their genetics can't have changed so it must be behavioral.

For your last point, it's really hard to actually work off a large number of calories. If people are really eating a lot, they can't typically do enough exercise to offset everything they eat.

Official definitions of obesity are tied to body mass index (BMI). BMI is calculated by dividing a person's weight in kilograms by their height in meters squared. A BMI of over 30 is considered obese by the World Health Organization. Obesity, like other medical conditions, can be tied to many different causes or a combination of them. Many people are genetically predisposed to obesity, others can have eating or metabolic disorders that may lead to increased weight gain, and obviously lifestyles can lead to weight gain as well.

Obesity is not a disorder, technically, but more like a ratio of fat to height. Obesity can be caused by gastric disorders, glandular disorders, etc. For people who do suffer from such disorders maintaining body weight can be a complex challenge. It isn't always as easy as exercising a little more or avoiding certain foods.

In general, staying active and eating healthy foods can combat obesity. Many people follow these very broad "guidelines" and find a happy balance that suits them.

I have always had a problem with my weight. My sister on the other hand has no problem with weight. She and I go to a restuarant and eat the same amount. I gain weight, but she does not. She actually eats more than I do. She eats desserts and I do not. It must have something to do with genetics because she takes after my mother's family. She is blond and fair like my mother's family. I take after my father's mother who also had a weight problem. I am dark haired and shaped like my father's grandmother. I do believe you can inherit weight problems.

I have always had a problem with my weight. My sister on the
other hand has no problem with weight. She and I go to a restuarant
and eat the same amount. I gain weight, but she does not. She
actually eats more than I do. She eats desserts and I do not. It
must have something to do with genetics because she takes after my
mother's family. She is blond and fair like my mother's family. I
take after my father's mother who also had a weight problem. I am
dark haired and shaped like my father's grandmother. I do believe
you can inherit weight problems.

true...but everyone is different and unique..everyone is
differently shaped and their body reacts differently and
yeah it can be through genetics ;)

I have long had a problem being overweight, as did my mother. However, my father weighed less than 150 pounds all his life, and both of my grandmothers barely weighed 100 pounds, so I'm not so sure about the genetic aspects of obesity. I can tell you that as a Southerner, my family ate a great deal of deep fried foods on a daily basis, and we usually had dessert for most meals, so our diet was far from perfect. I have lost about 130 pounds from my highest weight, and it came from a willingness to lose: counting calories, eating more healthily, exercising regularly, and saying no to foods that you may desire but should not eat.

We don't really know definitively what causes obesity. We do know there is a genetic component and that it often runs in families. We also know that people in general are not as active as we once were. Many of us live sedentary lifestyles and have little exercise. Previous generations had much more physical activity each day than we do. Some people do have disorders which contribute to obesity. For example, there are disorders of the pituitary gland which can cause weight issues unrelated to diet and exercise. Usually, obesity is caused by consuming too many calories for the person's particular metabolism and exercise level. This doesn't necessarily mean they sit around eating all day. A person will a naturally slow metabolism that does not get much exercise could quickly become obese.

Obesity can be tied to specific disorders. It is definitely possible for digestive disorders to contribute to obesity, because your body does not digest food as it should. Obesity can also be behavioral, because some people eat for other reasons and eat too much. There are also hormonal issues. Thyroid problems can cause obesity or at least contribute to it. An obese person should consult s physician and undergo all tests to see what causes it.

Obese:Well above ones normal weight. A person has traditionally been considered to be obese if they are more than 20 percent over their ideal weight. That ideal weight must take into account the person's height, age, sex, and build.

Obesity has been more precisely defined by the National Institutes of Health (the NIH) as a BMI of 30 and above. (A BMI of 30 is about 30 pounds overweight.) The BMI (body mass index), a key index for relating body weight to height, is a person's weight in kilograms (kg) divided by their height in meters (m)squared. Since the BMI describes the body weight relative to height, it correlates strongly (in adults) with the total body fatcontent. Some very muscular people may have a high BMI without undue health risks.

Obesity is often multifactorial, based on both genetic and behavioral factors. Accordingly, treatment of obesity usually requires more than just dietary changes. Exercise, counseling and support, and sometimes medication can supplement diet to help patients conquer weight problems. Extreme diets, on the other hand, can actually contribute to increased obesity.

Obesity can be caused by a number of reasons: hormones, health problems, emotions, love (of food) and at times genes. Health problems, like thyroid. Emotions, people after a loss of somebody in their lives tend to be depressd and go to food for comfort. Love, as it is, people just love having food in their mouths as it makes them feel good. And genes, that's nature's creation.

Regarding this question: even some persons rather they eat so much but they do work equal to nullify that much fats. Then why they become obese?

This ^ suits hormones, when some people eat some kind of food, for example fruits, they gain weight automatically. Its a weird thing, but doctors do say that these things happen with some people. So if the person never come to know that some food makes her/him fat, they'll keep on eating it and gain weight accordingly.

Well there are the people who honestly have the eating disorders in this case it is not there fault for there weight. However, Most of the over weight people I know are that way because they outright hate exercises. Also laziness is encouraged by our society with all the video games, TV, computers. Children nowadays would rather sit around rather than go outside. And the things in our food – fast food and junk food, all contribute to an over weight unhealthy generation. Some just don’t have a balanced way of life.